In my app before I send a string off I need to work out if the text entered in the textbox is a UK Postcode. I don't have the regex ability to work that out for myself and after searching around I can't seem to work it out! Just wondered if anyone has done a similar thing in the past?
Or if anyone can point me in the right direction I would be most appreciative!
Tom
Wikipedia has a good section about this. Basically the answer depends on what sort of pathological cases you want to handle. For example:
An alternative short regular expression from BS7666 Schema is:
[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][ABD-HJLNP-UW-Z]{2}The above expressions fail to exclude many non-existent area codes (such as A, AA, Z and ZY).
Basically, read that section of Wikipedia thoroughly and decide what you need.
for post codes without spaces (e.g. SE19QZ) I use: (its not failed me yet ;-) )
^([Gg][Ii][Rr] 0[Aa]{2})|((([A-Za-z][0-9]{1,2})|(([A-Za-z][A-Ha-hJ-Yj-y][0-9]{1,2})|(([A-Za-z][0-9][A-Za-z])|([A-Za-z][A-Ha-hJ-Yj-y][0-9]?[A-Za-z])))) [0-9][A-Za-z]{2})
if spaces (e.g. SE1 9QZ) , then:
^([Gg][Ii][Rr] 0[Aa]{2})|((([A-Za-z][0-9]{1,2})|(([A-Za-z][A-Ha-hJ-Yj-y][0-9]{1,2})|(([A-Za-z][0-9][A-Za-z])|([A-Za-z][A-Ha-hJ-Yj-y][0-9]?[A-Za-z])))) {0,1}[0-9][A-Za-z]{2})$
You can match most post codes with this regex:
/[A-Z]{1,2}[0-9]{1,2}\s?[0-9]{1,2}[A-Z]{1,2}/i
Which means... A-Z one or two times ({1,2}) followed by 0-9 1 or two times, followed by a space \s optionally ? followed by 0-9 one or two times, followed by A-Z one or two times.
This will match some false positives, as I can make up post codes like ZZ00 00ZZ, but to accurately match all post codes, the only way is to buy post code data from the post office - which is quite expensive. You could also download free post code databases, but they do not have 100% coverage.
Hope this helps.
Wikipedia has some regexes for UK Postcodes: http://en.wikipedia.org/wiki/Postcodes_in_the_United_Kingdom#Validation
